My partner and I were driving back to San Diego from Houston Tx. As we were approaching the grade into the mountains I spotted a craft heading for our truck. I yelled out " Dude, dude, dude a ufo!!!!! and pulled over immediatly. It was a spherus shaped craft with red, blue, green, and white lights. They were not many small lights but larger lights which covered the craft. It appeared to be tracking down the side of hwy 8 going east and rotating forward as if it was rolling through the air. It was the size of a 16 x 16 sphere. There was absolutelu no sound, noise or any sounds related to the craft as it passed us at about a 200 to 300 foot distance. We both watched it as it disapeared to the east.